Two years ago a purchased a 2011 Nissan Frontier mid-sized pick-up, V-6, A/T, 4WD, long-bed (6’), crew cab four door. I drove it for a little over a year and it was all good, then I put an 800 lb. pop-up cab-over camper on it. When folded down, the top of the camper is about one foot above the top of the truck cab, with about a four inch space between the bottom of the cab-over and the top of the cab, and with the cab-over extending over the back two-thirds of the cab, so the whole thing creates quite a bit of wind resistance. After installing the camper, I noticed a front-to-back jerking motion when driving the truck at highway speeds, sort of like when topping a steep hill and beginning to descend, some vehicles will lurch front-to-back until the drive train synchs up. It was cyclic – jerk 7 or 8 times, smooth out, then do it again. It wasn’t bad enough to cause vehicle control issues, but it was bad enough that my wife said it made her nausous. I took it to the dealer and the initial diagnosis was that the automatic trans. was going in and out of lock-up. Then I drove the service manager around in it with his laptop scope plugged in to the engine, and he said he couldn’t see anything wrong with the drive train. He suggested running the rear tires at maximum pressure of 44 lbs., which I tried but which didn’t work. I then had airbags installed to beef up the rear suspension, but that didn’t help. Finally I built a fairing/wind deflector and installed it on top of the cab, sloping at a 45 degree angle from the trailing edge of the windshield to the leading edge of the top of the camper. That didn’t help either, which surprised me because I had first experimented with the concept by duct-taping a sheet of cardboard in the same position as the fairing would ultimately be installed, and that seemed to help. The same jerking sensation can be felt when overdrive is engaged and when it is locked out, and it also occurs at slower speeds when decelerating. Is there anything I can do to smooth out the ride?
Remove the camper and see if the little truck starts driving normally again. If it does then the camper is simply overloading the truck. Mid-sized V-6 trucks are not good candidates to haul or tow campers. BTW…check your owner’s manual. Most of them advise you to turn off OD if you are hauling or towing. I speak from over 30 years experience In the RV world…as an owner and an employee.
I’d try super duty shocks. Wind resistance is pushing the camper backwards and down compressing the springs. I would be concerned with handling as I think at high speeds the front of the truck is relatively unweighted compared to the back end. In an emergency situation all hell could break loose. I think your truck is trying to tell you - danger. Are you listening?
It sounds to me like between the wind resistance and the 800lb weight (+ all the junk you’ve probably put in tghe camper) the poor tranny is struggling to maximize the engine efficieny. The only toll it has to do so it by shifting. Constantly. Up & down & up again.
In short, I think you’re pushing the truck’s limits. An 800 pound box entending above and to the sides of the cab places a far freater load on the drivetrain than an 800lb load of dirt. Stick your hand out the window while going down the highway some time and multiply that force by the thousands of times that would adjust for the difference between the surface area of the hand and the exposed surface area of the camper’s front surfaces.